This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Even with the success of antiretroviral drug therapy, considerable problems such as toxicity, viral resistance or latent infections provide an impetus to develop new therapeutic modalities. Gene therapy has been proposed as one alternative method. Multiple mechanism of inhibition have been developed (i.e. ribozymes, antisense, aptamers, RNAi, viral decoys, zinc finger nucleases, dominant negative proteins, and intrabodies) that target all phases of the viral lifecycle;however, it may be that an inhibitor that targets multiple points will provide more robust inhibition with reduced potential for viral escape. In RP Johnson's laboratory at NEPRC, we tested and compared multiple vector systems, inhibitors, and target populations. As an extension of this work, I am developing a two-phase viral inhibitor by combining the gp120-binding domain from CD4 with the heptad repeat sequences. Because gp120 and gp41 undergo extensive conformation changes during vial binding and fusion, we are hypothesizing that binding of the duel inhibitor to the viral envelope will open up gp120 and expose vulnerable sequences in gp41 for binding and inhibition by the heptad repeat sequences. This type of inhibitor could function either as a soluble protein, or tethered to the cell membrane. After variations of these inhibitors are finished being cloned and sequenced, they will be evaluated in T cell lines, primary T cells, and in rhesus macaque for efficacy in blocking viral replication.